At present, focal plane shutters are commonly used that employ imaging using a normally open system for a camera wherein, when capturing an image, one or more blade groups is driven to expose a photosensitive surface, and then, during standby, the image frame is opened, and the image is read in. Given this, in a focal plane shutter that employs image capturing using a normally open system, the use of a switching mechanism has been proposed to enable switching to image capturing in a normally closed system, wherein the image frame is closed during standby after the exposing operation.
Furthermore, shutters, such as those set forth in Japanese Unexamined Patent Application Publication Nos. 2011-137986 (“the JP '986”) and Japanese Unexamined Patent Application Publication 2011-113060 (“the JP '060”), are focal plane shutters that are currently used in cameras.
The focal plane shutters set forth in the JP '986 and the JP '060 are structured with a stopping member, provided with a movable element that can move in a rotational direction of a permanent magnet rotor, solenoid, or the like, or can undergo reciprocating action in a straight line direction, for preventing movement of a leading blade in the closing direction, to cause the exposure opening to be in an open state when in an image capturing standby state, and for releasing this prevention of movement of the leading blade in the closing direction at the time of imaging, structured from an electromagnetic device for moving the movable element in a direction that prevents the movement of the leading blade in the closing direction, or for moving the movable element in a direction that releases this prevention, through applying electric currents in two directions to a coil that is provided on the movable element. Given this, through switching the direction in which the electric current is applied to the coil of the movable element that is able to cause the reciprocating action of the stopping member that is made from an electromagnetic device at this time, the imaging in the normally open system is carried out by switching a first driving member for the leading blade into or out of an operating track of the portion that is to be stopped.
However, the use of a solenoid and/or permanent magnet rotor in a switching mechanism, as in the focal plane shutter set forth in the JP '986 and the JP '060, increases the cost. Moreover, the range of movement of the movable element in the permanent magnet rotor is limited, so the flexibility in the configuration is low. Moreover, because there is switching of the electric current in two directions in the electromagnetic device, the electric power consumption is increased commensurately.
The present invention was created in order to solve such a problem areas, and an aspect thereof is to provide a focal plane shutter for a camera, and a digital camera equipped therewith, wherein the cost of the switching mechanism is low, the flexibility of configuration of the actuator is high, and the electric power consumption is low, in a focal plane shutter of a type wherein it is possible to switch between imaging using a normally open system and imaging using a normally closed system.